#region Apache License
//
// Licensed to the Apache Software Foundation (ASF) under one or more 
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. 
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with 
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

using System;
using System.IO;

using log4net.Core;

namespace log4net.Util
{
    /// <summary>
    /// <see cref="TextWriter"/> that does not leak exceptions
    /// </summary>
    /// <remarks>
    /// <para>
    /// <see cref="QuietTextWriter"/> does not throw exceptions when things go wrong. 
    /// Instead, it delegates error handling to its <see cref="IErrorHandler"/>.
    /// </para>
    /// </remarks>
    /// <author>Nicko Cadell</author>
    /// <author>Gert Driesen</author>
    public class QuietTextWriter : TextWriterAdapter
    {
        #region Public Instance Constructors

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="writer">the writer to actually write to</param>
        /// <param name="errorHandler">the error handler to report error to</param>
        /// <remarks>
        /// <para>
        /// Create a new QuietTextWriter using a writer and error handler
        /// </para>
        /// </remarks>
        public QuietTextWriter(TextWriter writer, IErrorHandler errorHandler)
            : base(writer)
        {
            if (errorHandler == null) {
                throw new ArgumentNullException("errorHandler");
            }
            ErrorHandler = errorHandler;
        }

        #endregion Public Instance Constructors

        #region Public Instance Properties

        /// <summary>
        /// Gets or sets the error handler that all errors are passed to.
        /// </summary>
        /// <value>
        /// The error handler that all errors are passed to.
        /// </value>
        /// <remarks>
        /// <para>
        /// Gets or sets the error handler that all errors are passed to.
        /// </para>
        /// </remarks>
        public IErrorHandler ErrorHandler
        {
            get { return m_errorHandler; }
            set
            {
                if (value == null) {
                    // This is a programming error on the part of the enclosing appender.
                    throw new ArgumentNullException("value");
                }
                m_errorHandler = value;
            }
        }

        /// <summary>
        /// Gets a value indicating whether this writer is closed.
        /// </summary>
        /// <value>
        /// <c>true</c> if this writer is closed, otherwise <c>false</c>.
        /// </value>
        /// <remarks>
        /// <para>
        /// Gets a value indicating whether this writer is closed.
        /// </para>
        /// </remarks>
        public bool Closed
        {
            get { return m_closed; }
        }

        #endregion Public Instance Properties

        #region Override Implementation of TextWriter

        /// <summary>
        /// Writes a character to the underlying writer
        /// </summary>
        /// <param name="value">the char to write</param>
        /// <remarks>
        /// <para>
        /// Writes a character to the underlying writer
        /// </para>
        /// </remarks>
        public override void Write(char value)
        {
            try {
                base.Write(value);
            }
            catch (Exception e) {
                m_errorHandler.Error("Failed to write [" + value + "].", e, ErrorCode.WriteFailure);
            }
        }

        /// <summary>
        /// Writes a buffer to the underlying writer
        /// </summary>
        /// <param name="buffer">the buffer to write</param>
        /// <param name="index">the start index to write from</param>
        /// <param name="count">the number of characters to write</param>
        /// <remarks>
        /// <para>
        /// Writes a buffer to the underlying writer
        /// </para>
        /// </remarks>
        public override void Write(char[] buffer, int index, int count)
        {
            try {
                base.Write(buffer, index, count);
            }
            catch (Exception e) {
                m_errorHandler.Error("Failed to write buffer.", e, ErrorCode.WriteFailure);
            }
        }

        /// <summary>
        /// Writes a string to the output.
        /// </summary>
        /// <param name="value">The string data to write to the output.</param>
        /// <remarks>
        /// <para>
        /// Writes a string to the output.
        /// </para>
        /// </remarks>
        override public void Write(string value)
        {
            try {
                base.Write(value);
            }
            catch (Exception e) {
                m_errorHandler.Error("Failed to write [" + value + "].", e, ErrorCode.WriteFailure);
            }
        }

        /// <summary>
        /// Closes the underlying output writer.
        /// </summary>
        /// <remarks>
        /// <para>
        /// Closes the underlying output writer.
        /// </para>
        /// </remarks>
        override public void Close()
        {
            m_closed = true;
            base.Close();
        }

        #endregion Public Instance Methods

        #region Private Instance Fields

        /// <summary>
        /// The error handler instance to pass all errors to
        /// </summary>
        private IErrorHandler m_errorHandler;

        /// <summary>
        /// Flag to indicate if this writer is closed
        /// </summary>
        private bool m_closed = false;

        #endregion Private Instance Fields
    }
}
